Lubrication of synthetic cellulose fibers



2,872,356 Patented-Feb. 3, 1959 LUBRICATION F SYNTHETIC CELLULOSE FIBERSHarry W. Bull, Midland, and Walter A. Finke, Saginaw,

Mich., assignors to The Dow Chemical Company, Midland, Mich., acorporation of Delaware No Drawing. Application June 2, 1955 Serial No.512,852

3 Claims. (01. 117-1395 This invention relates to the sewing ofsynthetic cellulosic fibers.

It has long been known that the needles of commercial sewing machinesfrequently become hot during operation at high speeds. Consequentlythermoplastic threads such as those of synthetic cellulosic fiberssoften during sewing. Under these conditions the least stoppage maycause the filaments to fuse together in the eye of a needle with theresultant breaking of the thread when the sewing is resumed or the speedis increased. It has also been found that the action of the needle tendsto cut thermoplastic threads thereby causing injury to the fabric.

Attempts to alleviate this difliculty have previously been made withorganic dressings such as waxes, mineral oils, vegetable oils and thelike. It has been found, however, that many of these heretofore employedthread dressings tend to dissolve synthetic fibers and thereforeappreciably reduce their strength. This is particularly true of yarnscomposed of synthetic cellulosic materials. Furthermore yarns which havebeen treated with these conventional lubricants have little or noprotection against the heat developed in the needle of the machine.

It is the object of this invention to provide a treatment forsyntheticcellulosic fibers which will enable them to be satisfactorilysewn. Other objects and advantages will be apparent from the followingdescription.

This invention relates to a sewing thread composed of syntheticcellulosic fibers, which have been impregnated with a fluiddiorganopolysiloxane in which the organic radicals are monovalenthydrocarbon radicals attached to the silicon atom through silicon-carbonlinkages.

It has been found that threads coated with these fluid organosiloxanescan be sewn with case without any appreciable reduction in the tensilestrength of the fibers. This invention makes possible the commercialsewing of ethyl cellulose threads which heretofore could not besatisfactorily sewn on commercial machines even when treated withconventional organic thread coating materials.

The organopolysiloxanes operative in this invention are any fluidmonovalent hydrocarbon substituted siloxane. Suitable examples of suchsiloxanes are those of the unit formula R SiO or R SiO and copolymers ofthese siloxanes. The fluids may also contain monoorganosiloxane unitsand SiO units.

For the purpose of this invention the hydrocarbon radicals on thesilicon can be any monovalent hydrocarbon radical such as alkyl radicalssuch as methyl, ethyl and octadecyl; alkenyl radicals such as vinyl,allyl or hexenyl; cycloaliphatic hydrocarbon radicals such as cyclohexylor cyclohexenyl; aryl hydrocarbon radicals such as phenyl, tolyl, xenyland naphthyl; and aralkyl hydrocarbon radicals such as benzyl.

Any synthetic cellulosic fiber is included within the scope of thisinvention. These include, for example, cellulose ethers such as methylcellulose, ethyl cellulose, propyl cellulose and benzyl cellulose;cellulose esters such as cellulose acetate, cellulose propionate andcellulose butyrate and regenerated cellulose.

, or spraying.

The organosiloxane may be applied to the fibers in any convenientmanner. The precise mode of application will depend largely upon thenature of the material and the use for which it is intended. In general,

'the thread dressing or lubricant may be applied by any of the standardprocedures such as by dipping, padding It is frequently advantageous toapply the siloxane to the thread in solution of an organic solvent suchas petroleum ether, toluene, benzene and the like.

For the purpose of this invention the viscosity of the siloxane is notcritical and it may range from thin fluids to soluble gums.

The following examples are illustrative only and should not be construedas limiting the invention which is properly delineated in the appendedclaims.

Example 1 A liquid dimethylsiloxane polymer having a viscosity of 5,200cs. at 25 C. was dissolved in an equal weight of petroleum ether. Ethylcellulose thread of 1,800 denier yarn was passed through the solutionand then wiped on felt to remove the excess liquid. The thread was woundon a cone and was used to sew filter bags made of ethyl cellulose twillwoven cloth. The sewing machine operated satisfactorily at a speed of2,000 to 3,000 stitches per minute. In contrast, ethyl cellulose threadof the same construction which had been coated with a vegetable baselubricant, fused and broke readily on the same machine operated at aspeed of 1,000 to 1,500 stitches per minute.

Portions of the above thread were tested for tensile strength. Thethread coated with the dimethylsiloxane polymer showed no loss intensile strength at the end of two or three days storage at roomtemperature. By contrast the thread coated with the vegetable baselubricant had lost three pounds in tensile strength after storage atroom temperature for two to three days.

Example 2 Ethyl cellulose thread similar in quality to that employed inExample 1 was coated with a liquid dimethylpolysiloxane having aviscosity of 302 cs. at 25 C. The excess liquid was removed by wipingwith felt and the coated thread was tested for abrasion resistance asfollows: The thread was wound wrap) on a 5 inch diameter polished wireand then pulled with a six inch stroke back and forth around the wire ata tension of 500 grams. The number of strokes required to break thethread was determined.

The siloxane coated thread ran for 59 strokes. By contrast an identicaltype thread coated with a commercial vegetable base spinning oil brokeafter 38 strokes under identical test conditions.

Example 3 Improved sewing is obtained when the following fluid siloxanesare employed in the procedure of Example 1: phenylmethylsiloxane,ethylmethylsiloxane, octadecylmethylsiloxane, vinylmethylsiloxane,vinylphenylsiloxane, copolymers of dimethylsiloxane andtrimethylsiloxane, copolymers of diethylsiloxane, monomethylsiloxane andphenyldimethylsiloxane and copolymers of trimethylsiloxane and SiOExample 4 Improved sewing qualities are obtained when cellulose acetatethreads are treated in accordance with the procedure of Example 1.

That which is claimed is:

1. A sewing thread composed of synthetic cellulosic fibers, said threadbeing coated with a fluid organopoly- References Cited in the file ofthis patent UNITED STATES PATENTS Kropscott et'al. Jan. 10, 1950 DodgeOct. 10, 1950 James May 5, 1953 Guenther Jan. 4, 1955

1. A SEWING THREAD COMPOSED OF SYNTHETIC CELLULOSIC FIBERS, SAID THREADBEING COATED WITH A FLUID ORGANOPOLYSILOXANE IN WHICH THE ORGANICRADICALS ARE MONOVALENT HYDROCARBON RADICALS, SAID THREAD BEING MORERESISTANT TO INFUSION BREAKS AND MORE EASILY SEWN THAN SIMILAR THREADSOF THE SAME COMPOSITION WHICH HAVE NOT BEEN TREATED WITH THE SILOXANE.